What Is NDT? (Definition, Uses and Common Benefits)

By Indeed Editorial Team

Published August 25, 2021

The Indeed Editorial Team comprises a diverse and talented team of writers, researchers and subject matter experts equipped with Indeed's data and insights to deliver useful tips to help guide your career journey.

NDT is a technique that industries use to test the properties of a material and identify potential defects. There are various industries that use NDT, such as automotive, aerospace and oil and gas. If you work as an engineer or are looking for work in an industry that uses NDT, you might want to learn about what it is and how you can use it. In this article, we define what NDT is and explore its benefits, as well as some of its most common methods and uses.

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What is NDT?

NDT, which stands for nondestructive testing, is a technique for testing and analyzing materials. Most often, the professionals who conduct NDT are engineers or other types of professionals who work in industrial positions. Performing an NDT can tell an engineer about the properties of a specific material, such as how strong it is. It can also indicate any differences between units of the same material, which can help identify potential defects.

Because NDT is nondestructive, it doesn't cause any damage to the original product or material being tested. This can be helpful when a product needs only a small adjustment to be effective, as manufacturers can make the changes without having to produce a completely new piece of material.

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How is NDT used?

Professionals can use NDT in a wide variety of ways. One common use for NDTs is to make sure that the components of a system function effectively by testing each component as its own material, then observing how they work together. Another popular use for NDTs is to identify and characterize details that might have the potential to cause errors in the future, such as a reactor with a part that might cause it to fail or a plumbing system that might cause pipes to burst.

Industries also use NDT as a form of cost-effective quality control, as it doesn't damage the materials it evaluates, which can reduce waste and expenses.

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Benefits of using NDT

Using NDT can have many benefits, such as preserving the original material being tested. The process accomplishes this by using nondestructive methods to analyze materials, which allows for engineers to adjust them as needed without performing more work than is necessary. The nondestructive nature of NDT can also benefit a company by minimizing the waste that it experiences by reducing the need for rebuilding materials or systems that have small defects. Another benefit to using NDT is that it can tell a team about a material's properties, such as how tough it is or how formable it is.

NDT methods

Here are a few of the most common methods for conducting NDT:

Visual and optical testing

Visual and optical testing is often considered the most popular method of NDT. This is because it can be easy to perform, as it typically focuses on visual examination. When conducting visual and optical testing, professionals can inspect the surfaces of a product or machine part to identify any clear imperfections right away. They can also use camera systems to inspect the features and to measure the different areas of a component or material.

Radiography testing

Radiography testing uses radiation to examine the internal features of a piece of material or component in a system. Some of the most common types of radiation that professionals use in radiography testing can include gamma-radiation or X-radiation, as these types of radiation aren't destructive or damaging. After conducting a radiography test, specialists can review the shadowgraphs that the test produces to look for soundness and density consistency throughout the material being tested.

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Magnetic particle testing

Magnetic particle testing employs magnetic fields to quickly scan metal materials for surface claws. The process accomplishes this by creating a magnetic field and covering the surface of the item being tested with iron particles. This causes the magnetic field to leak from any part of the item that has a flaw, such as a scratch, hole or crack, which attracts the iron particles to indicate where the flaw is. Once the testing is complete, inspectors can quickly note where the surface defects are so they can repair them before testing the item again.

Ultrasonic testing

Ultrasonic testing uses sound waves to identify potential imperfections on the exterior and within the interior of a piece of material. Similar to radiography testing, professionals transmit waves through a piece of material and produce echoes or reflections that indicate where imperfections are present. This information transmits back to a receiver that the testers can easily read and interpret to determine their next steps.

Penetrant testing

Penetrant testing involves covering an object with a liquid solution that has dye in it. Most professionals use some type of fluorescent dye, as the colors appear brightly in normal lighting and also can glow under ultraviolet light. After coating the item being tested, the tester can pour any excess liquid off of the surface, only leaving behind colored solution in places where surface defects are present, such as cracks or holes. The solution in the defective areas stands out clearly from the rest of the object's surface, allowing testers to easily see the defects they might need to fix.

Acoustic emission testing

Acoustic emission testing is most common in industries that produce items that are intended to manage high volumes of stress, like bridges and other construction projects. In acoustic emission testing, a team applies pressure to an object to determine whether it has any cracks or other imperfections. They can tell this because any area that has an imperfection can leak emissions or ultrasound after it experiences pressure. The team can then make a note of any leaks and take the next steps to fortify the areas that need to be stronger.

Ground-penetrating radar testing

This type of testing can be especially valuable during construction projects, as it can identify inconsistencies that occur in natural materials beneath the ground's surface, like rock, ice or soil. Ground-penetrating radar testing works by pulsing radar through the surface of the material being tested, which is then reflected or refracted back when they find a foreign object. Professionals can then use this information to clear a potential worksite of any objects that might pose hazards.

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